Various types of digital image capture (or image reading) devices are available in the prior art. More particularly, various types of image capture devices are available in the prior art for obtaining a digital image of an original image. For example, image capture devices such as scanners (both handheld and flatbed) for personal computers, digital cameras, facsimile machines, and digital copying machines are available in the prior art. As discussed below, digital image capture devices of the prior art typically do not provide convenient, space-efficient means for capturing a digital image with a high resolution. For instance, prior art digital image capture devices are not suitable for space-efficient use on a desktop to capture digital images with sufficient resolution for use in an optical character recognition (OCR) program.
Traditional image capture devices, such as scanners and copying machines, typically include a frame having a platen glass on top thereof on which an original is placed face down for capturing an image of such original. An example of a typical flatbed scanner 100 of the prior art is shown in FIG. 1. As shown, a light source 102 illuminates an original image 104 (e.g., a piece of paper) that is placed face down against a platen glass window 106 positioned above the scanning mechanism (e.g., scan head) 108. In general, blank or white spaces on original 104 reflect more light than do inked or colored letters or images on original 104. Typically, a motor moves scan head 108 beneath original 104, and as it moves, scan head 108 captures light bounced off individual areas of original 104.
The light from original 104 is reflected through a system of mirrors, such as mirrors 110A, 110B, and 110C, that maintain the reflected light beams aligned with a lens 112. Lens 112 focuses the beams of light onto a solid-state image pick-up device (e.g., light-sensitive diodes) 114 that translates the amount of light into an electrical current. More specifically, lens 112 typically focuses the beams of light onto a coupled-charge device (CCD) 114, which converts the light energy (or intensity) into electrical current. Generally, the more light that is reflected (i.e., the greater the intensity), the greater the voltage or current produced. Of course, some digital imaging devices are implemented in a manner such that the greater the intensity of the reflected light the lesser the voltage or current produced. If scanner 100 works with colored images (i.e., is a color scanner), the reflected light is typically directed through red, green, or blue filters (not shown) in front of separate diodes to enable scanner 100 to determine the appropriate color images of original 104. Other color separation methods also exist and are well known in the art. An analog-to-digital converter (ADC) 116 stores each analog reading of voltage as a digital pixel representing the light's intensity for a spot along a line that typically contains 300 to 1,200 pixels to the inch. The digital information (i.e., the captured digital image) may be utilized in a variety of ways thereafter. For instance, the digital information may be sent to software in a PC (e.g., via coupling 118 with a PC), wherein the data may be stored in a format with which a graphics program or an OCR program can work.
Such flatbed scanners are commonly available in the prior art, and examples of such prior art flatbed scanners include scanners commercially available from Hewlett-Packard, such as the scanners commercially marketed as “HP ScanJet” (e.g., models 3300Cse, 4200Cse, 6200Cse, and 6390C).
As described above, such prior art digital imaging devices have traditionally been relatively large in size, and therefore would generally consume a relatively large amount of surface area if placed on a desktop. Furthermore, such prior art digital imaging devices generally limit the types of original images that may be captured. For example, traditional prior art digital imaging devices, such as flatbed scanners, do not enable the capture of 3-dimensional (“3D”) objects. For instance, the light source of such traditional digital imaging devices (e.g., light source 102 of FIG. 1) is typically focused at the place where the original image is intended to be placed on the platen (e.g., platen 106 of FIG. 1), and as an original is moved away from the platen surface (or has features that extend away from the platen surface) the light diminishes rapidly resulting in inability to accurately capture any portion that is removed from the platen surface (or the lens of the imaging device is otherwise unable to maintain the portion of the original that is removed from the platen surface in focus). Accordingly, traditional prior art digital imaging devices, such as flatbed scanners, have limited ability to capture 3D originals.
Also available in the prior art are hand-held scanners, which a user holds and manually translates across an original to capture a digital image of such original. While such hand-held scanners are space-efficient in that they do not require that a portion of a desktop surface, for example, be dedicated solely for such scanner, various problems are associated with the use of such hand-held scanners. Such problems arise primarily from the hand-held scanners* heavy reliance on the manual translation by a user in order to perform a scan. For example, the rate at which the user translates the scanner across an original is not fixed, and is therefore unpredictable. An inappropriate translation speed often results in distortions in a captured digital image. Use of such hand-held scanners are further problematic in that as a user scans an original, the user is necessarily covering up what the user is attempting to scan. Therefore, it is difficult for a user to accurately scan portions of an original because the original is covered as the user translates the scanner across such original. Also, as a user translates a hand-held scanner across an original, the user may apply too much pressure against the original and drag such original across the desktop.
More recently, digital document cameras have become commercially available. For example, a prior art digital document camera is commercially available from Canon, such as Canon's digital document camera model DZ-3600U. As with the more traditional digital imaging devices discussed above, such digital document cameras of the prior art typically include a platen on which an original document is placed. An example of a typical digital document camera 200 of the prior art is shown in FIG. 2. As shown, a light source 202 illuminates an original image (e.g., a piece of paper) that is placed face up on a platen 204 positioned substantially beneath a digital camera 206. Digital camera 206 may be a digital camera for capturing still images or it may be a video camera for performing video recording. Once digital camera 206 captures a digital image of the original placed on platen 204, the digital image may be stored in a computer, and the digital image may be transmitted from such a computer to others via a network (e.g., a WAN, LAN, the Internet, or an Intranet).
However, digital camera 206 generally provides a relatively low-resolution digital image of the original. For instance, digital document cameras of the prior art typically do not provide sufficient resolution to enable OCR operations, for example, as with the above-described flatbed scanners. As an example, Canon's digital document camera model DZ-3600U provides a resolution of 1900 pixels by 1424 pixels, which may provide an image that is legible to a user for text of 8 point font or larger, but is insufficient resolution for performing OCR operations or other types of imaging operations requiring greater resolution. Additionally, modifying digital camera 206 to enable an increase in the resolution of a captured image appears to be a relatively expensive proposition. That is, digital camera sensors that enable such a high resolution (e.g., three mega-pixels or more) are very expensive. As a comparison, to provide the equivalent resolution of a 300 dots per inch (dpi) scanner, which is a very low end scanner of the prior art, a digital document camera would need to have approximately an 8 to 10 mega-pixel camera. Accordingly, the resolution of digital document cameras of the prior art is very inferior to that of prior art scanners, and modifications required for a digital document camera to approach the resolution of prior art scanners are very expensive.
As with the above-described traditional digital imaging devices (e.g., flatbed scanners), digital document cameras are relatively large in size, and therefore generally consume a relatively large amount of surface area (e.g., of a desktop on which it is placed). For instance, a prior art digital document camera as described in conjunction with FIG. 2 having platen 204 would typically consume a relatively large amount of surface area on a desktop. While prior art digital document cameras may allow for the capture of a digital image of a 3D object (which is generally unavailable with more traditional digital imaging devices, such as flatbed scanners), the resolution of such digital document cameras is relatively poor. As described above, prior art digital document cameras typically capture a digital image having insufficient resolution for performing OCR operations or other types of imaging operations requiring greater resolution. Additionally, modifying such digital document cameras to enable an increase in the resolution of a captured image appears to be a relatively expensive proposition due to the relatively high cost of digital camera sensors.
Moreover, attempts to provide a suitable look-down digital imaging device that does not include the platen of the above-described digital document cameras (e.g., platen 204 of FIG. 2) in order to be more space-efficient have been disclosed in the prior art. For example, U.S. Pat. No. 5,227,896 issued to Takashi Ozawa entitled “IMAGE READER FOR PRODUCING AND SYNTHESIZING SEGMENTED IMAGE DATA” and U.S. Pat. No. 5,515,181 issued to Tetsuo Iyoda entitled “IMAGE READING APPARATUS PROVIDING HIGH QUALITY IMAGES THROUGH SYNTHESIS OF SEGMENTED IMAGE DATA” each disclose a look-down digital imaging device. However, the look-down digital imaging devices as disclosed in these patents capture multiple segments of an original image and then synthesize such segments to form a digital image of the original. Such capture of multiple segments and synthesis of the multiple segments is a relatively complex process. For instance, such digital imaging method is much more complex than the above-described digital imaging method typically utilized in flatbed scanners, which capture a single, congruent digital image thereby avoiding the synthesis of multiple image segments. As described above, look-down digital imaging devices, such as digital document cameras, generally have relatively poor resolution, as compared to that of typical flatbed scanners, for example. Thus, the relatively complex process of capturing multiple image segments and synthesizing such segments to form a digital image is performed in an attempt to overcome such limited resolution of prior art look-down digital imaging devices. Such added complexity to a look-down digital imaging device may substantially increase the production costs of such a look-down digital imaging device.